Procedure for purifying phosphoric acid. (Machine-translation by Google Translate, not legally binding)

摘要

Procedure for purifying phosphoric acid, with a concentration in P2O5 of between 10 and 30%, preferably between 10 and 20% by weight, obtained by acidification of a phosphate mineral with sulfuric acid, characterized in that in a first stage, it is adjusted the calcium ion content of said phosphoric acid between 0} 25 to 3%, preferably between 1 to 3% by weight calculated as CaO; in a second stage, hydrofluoric acid is added to said phosphoric acid in sufficient quantity to react with all the cationic impurities; in a third stage, calcium fluoride is precipitated and insoluble magnesium, iron and aluminum are co-precipitated; in a fourth stage, the precipitated calcium fluoride as well as the aforementioned insolubles are separated from the supernatant phosphoric acid and, in a fifth and last stage, the phosphoric acid with a significantly reduced content of impurities is recovered. (Machine-translation by Google Translate, not legally binding)